Percutaneous catheter directed intravascular occlusion devices

ABSTRACT

The present invention provides an improved vascular occlusion device having improved flexibility and retention of the type fabricated from braided tubular metal fabric having an expanded preset configuration and an elongated collapsed reduced diameter configuration for delivery through a catheter to a treatment site and shaped to create an occlusion of an abnormal opening in a body organ or vessel, the woven metal fabric having a memory property whereby the medical device tends to return to said expanded preset configuration when unconstrained. The device further including at least one disk portion adjacent a body cylindrical portion formed from the fabric and having a transition diameter between the disk and cylindrical portion, significantly smaller than the diameter of the disk and the diameter of the cylindrical portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/216,784, filed Aug. 24, 2011, titled “Percutaneous Catheter DirectedIntravascular Occlusion Devices,” which is a divisional of U.S.application Ser. No. 11/827,590 (now Pat. No. 8,034,061), filed Jul. 12,2007, which is hereby incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to intravascular devices fortreating certain medical conditions and, more particularly, relates tointravascular occlusion devices for selective occlusion of a vesselanywhere in the body's circulatory system where it is desired to stopthe flow of blood. The devices made in accordance with the invention areparticularly well suited for delivery through a catheter or the like toa remote location in a patient's vascular system within a patient's bodywhereby a passageway to be occluded, has an axis and at least oneaperture which intersects another vessel wall somewhat perpendicular tothe axis.

2. Description of the Related Art

A wide variety of intravascular devices are used in various medicalprocedures. Certain intravascular devices, such as catheters andguidewires, are generally used simply to deliver fluids or other medicaldevices to specific locations within a patient's body, such as aselective site within the vascular system. Other, frequently morecomplex, devices are used in treating specific conditions, such asdevices used in removing vascular occlusions or for treating septaldefects and the like.

In certain circumstances, it may be necessary to occlude a patient'svessel, chamber, channel, hole or cavity such as to stop blood flowthere through.

Mechanical embolization devices are well known in the art and soldcommercially for occlusion of vessels in various locations within thevasculature. U.S. Pat. No. 6,123,715 by Amplatz and U.S. Pat. No.5,725,552 by Kotula disclose intravascular occlusion devices fabricatedfrom Nitinol braided metal fabric which are heat-set in molds to anexpanded shape, but which can be compressed for delivery through acatheter to a treatment site, whereby the device, when urged out of thedelivery catheter, self expands within the vasculature to occlude bloodflow at the treatment site. The details of the various designs andconfigurations, as well as methods of fabricating and using the devices,are detailed in the aforementioned patents and incorporated in totalherein by reference.

Although the occlusion devices described by Amplatz and Kotula patentsare quite effective, there are significant improvements that can bemade. In the Amplatz U.S. Pat. No. 5,725,552, there are described, inFIGS. 6A-C, and 11-18, two occlusion devices, each of which incorporatesdisk elements at one or both ends. The devices further incorporate acylindrical portion with a diameter smaller than the disk maximumdiameter and extending with an axis generally perpendicular to the planeof the disk. An example of this prior art is shown in FIGS. 1A, 1B and 2hereof. The mentioned prior art devices do not always align themselvesas well as possible to the anatomical conditions due to the lack ofbending flexibility between the cylindrical portion and the diskportion. This occurs when the vessel wall containing the aperture of thevessel to be occluded is not quite perpendicular to the axis of thevessel to be occluded. In the case of double disked occluders for use,for example, in Ventricular Septal Defects (VSD), Atrial Septal Defects(ASD) and Patent Foraman Ovale (PFO) and the like, it may be thatneither wall is perpendicular to the passageway or aperture to beoccluded. When this occurs, with the prior art devices, the diskattempts to align, but it's lack of flexibility causes portions of thedisk to extend further from the vessel wall than desired which mayinterfere with blood flow or cause gaps between portions of the disk andthe vessel wall.

The prior art devices represented by the Amplatz and Kotula patents,with a single disk, are retained in place, as deployed, by sizing thecylindrical portion diameter larger in its unrestrained self expandingcondition larger than the diameter of the vessel to be occluded. Thisimparts a load from the Nitinol braid's desire to expand larger to beimparted against the body lumen tissue to secure the device in place.Due to lack of precision in estimating the diameter of the vessel to beoccluded or the body's ability to yield or dilate in response topressure changes, and movement of the body, the retention force canoccasionally be insufficient to retain the device in place as desired.

Accordingly, it would be advantageous to provide an improved occlusiondevice which offers increased flexibility between the disk and thecylindrical diameter for better disk alignment to the aperture wall andalso to improve the retention of the device, particularly in a singledisk occluder device.

SUMMARY OF THE INVENTION

The present invention is well suited for the selective occlusion of avessel, lumen, channel, or cavity having an axis and at least oneaperture which intersects another vessel wall somewhat perpendicular(+or 45 degrees) to the axis. One example, without limitation, of such acondition is a Patent Ductus Arteriosus (hereinafter PDA). Anotherexample is a vessel, lumen, channel, or hole through which blood flowsfrom one vessel to another vessel such as an Atrial Septal Defect(herein after ASD) or a Ventricular Septal Defect (herein after VSD).Another example could be an arterial venous fistula (AVF) or arterialvenous malformation (AVM).

When forming these intravascular devices from a resilient metal fabric,a plurality of resilient strands is provided, with the wires beingformed by braiding to create a resilient metallic fabric which can beheat treated to substantially set a desired shape. This braided fabricis then deformed to generally conform to a molding surface of a moldingelement and the braided fabric is heat treated in contact with thesurface of the molding element at an elevated temperature. The time andtemperature of the heat treatment is selected to substantially set thebraided fabric in its deformed state. After the heat treatment, thefabric is removed from contact with the molding element and willsubstantially retain its shape in the deformed state. The braidedfabric, so treated, defines an expanded state of a medical device whichcan be deployed through a catheter into a channel in a patient's body.

Embodiments of the present invention provide specific shape improvementsover prior art medical devices to address occlusion of vessels havingspecific anatomical conditions. Such devices of the present inventionare formed of a braided metal fabric and have an expanded configurationand a collapsed configuration. In use, a guide catheter can bepositioned in a channel in a patient's body and advanced to position thedistal end of the catheter adjacent a treatment site for treating aphysiological condition. A medical device, formed in a predeterminedshape, and made in accordance with the process outlined above, can becollapsed and inserted into the lumen of the catheter. The device isurged through the catheter and out the distal end, whereupon, due to itsmemory property, it will tend to substantially return to its expandedstate adjacent the treatment site. In accordance with a first of theseembodiments, a generally elongate medical device has a generallycylindrical middle portion and a pair of expanded diameter diskportions, with one expanded diameter portion positioned at either end ofthe middle portion. In another embodiment, the medical device isgenerally bell-shaped, having an elongate cylindrical portion having atapered first end and a larger diameter second disked end, the secondend presenting a fabric disc which will be oriented generallyperpendicular to an axis of a vessel, channel, lumen, or cavity whendeployed therein.

The inventive device improves the flexibility between the disk portionand the cylindrical middle portion by providing a very small transitiondiameter between the disk portion and middle portion, the transitiondiameter being much smaller than the middle portion diameter. This smalltransition diameter allows the disk to easily flex about this diameterto orient itself to the wall of the vessel containing the aperture toaccommodate a wide range of anatomical variations between the axis ofthe lumen to be occluded and the wall containing the aperture to thelumen.

By recessing the portion having the small transition diameter within anindentation formed in the end of the cylindrical middle portion of thedevice, exact positioning of the device within a vessel is not overlycritical. The recess allows the disk and cylindrical portion to remainin close proximity as they are in free space or will also allow the diskand cylindrical portion to separate a small distance while stillmaintaining device function.

The improved single disk device also has improved retention whencompared to the prior art by the addition of flexible Nitinol shapememory wires sutured or fastened to or a part of the braided structuremiddle portion. The wires have a resilient hook end, designed to extendoutward from the device middle portion surface, upon deployment, toreversibly engage the vessel wall to resist motion of the device towardthe disk end. The hook end has no barb and allows the device to berepositioned by device movement opposite in direction (away from disk)to the pointed end of the hook. The device may also be withdrawn backinto the delivery catheter after deployment by resiliently un-bendingthe hook as it is drawn back into the distal end of the catheter. Thehook shaped wires add additional device retention to that provided bythe sizing of the middle portion diameter larger than the vessel to beoccluded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B depict the prior art single disk occluder device;

FIG. 2 is an enlarged side elevation view of another prior art device;

FIG. 3 is a cross-sectional view of the device like that of FIG. 2 butshowing the inventive modification for improved disk flexibility foralignment to anatomy variations;

FIG. 4 is a side elevational view of the prior art ASD device, shownstretched and filled with polyester fibers;

FIG. 5A is a cross-sectional view of a single disk device in accordancewith the present invention;

FIG. 5B is a perspective view of the inventive device of FIG. 5A;

FIG. 6 is a partially exploded assembly view of an alternative singledisk device and delivery apparatus;

FIGS. 7A through 7C depict progressive stages of deployment of thesingle disk occluder of FIGS. 5A and 5B.

FIG. 8A depicts an ASD or VSD occluder made in accordance with thepresent invention shown in its pre-shaped configuration having doubledisks of the same diameter, each disk dished inward with a gap betweenthe disks;

FIG. 8B is a cross-sectional view of the device of FIG. 8A showing theinventive modification for improved disk flexibility and alignment toanatomy;

FIG. 8C is a cross-sectional view of the device of FIG. 3 showing theinventive modification to improve disk flexibility and alignment toanatomy variations;

FIG. 9 is a partial sectional side elevational view of the ASD device ofFIG. 2-4 shown positioned within an ASD of a patient's heart; and

FIG. 10 is a cross-sectional view of an occlusion device of theinvention showing the disks conforming to the walls in the occlusion ofa VSD.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides an improved percutaneous catheterdirected intravascular occlusion device for use in the vasculature inpatients' bodies, such as blood vessels, channels, lumens, a holethrough tissue, cavities and the like. In forming a medical device ofthe invention, a metal fabric is formed of a plurality of wire strandshaving a predetermined relative orientation between the strands.

The metal strands define two sets of essentially parallel generallyhelical strands, with the strands of one set having a “hand”, i.e. adirection of rotation, opposite that of the other set. This defines agenerally tubular fabric, known in the fabric industry as a tubularbraid. The Amplatz and Kotula patents previously discussed describemedical devices and the methods of fabrication of such devices in greatdetail and detailed further discussion is not needed.

The pitch of the wire strands (i.e. the angle defined between the turnsof the wire and the axis of the braid) and the pick of the fabric (i.e.the number of wire crossovers per unit length) may be adjusted asdesired for a particular application. The wire strands of the metalfabric used in the present method should be formed of a material whichis both resilient and which can be heat treated to substantially set adesired shape. Materials which are suitable for this purpose include acobalt-based low thermal expansion alloy referred to in the field asElgeloy, nickel-based high temperature high-strength “superalloys”commercially available from Haynes International under the trade nameHastelloy, nickel-based heat treatable alloys sold under the nameIncoloy by International Nickel, and a number of different grades ofstainless steel. The important factor in choosing a suitable materialfor the wires is that the wires retain a suitable amount of thedeformation induced by the molding surface (as described below) whensubjected to a predetermined heat treatment.

One class of materials which meet these qualifications is so-calledshape memory alloys. One particularly preferred shape memory alloy foruse in the present method is Nitinol. NiTi alloys are also veryelastic—they are said to be “superelastic” or “pseudoelastic”. Thiselasticity will help a device of the invention return to a presentexpanded configuration for deployment following passage in a distortedform through a delivery catheter.

In forming a medical device in keeping with the invention, anappropriately sized piece of the metal fabric is cut from the largerpiece of fabric which is formed, for example, by braiding wire strandsto form a long tubular braid. When cutting the fabric to the desireddimensions, care should be taken to ensure that the fabric will notunravel.

One can solder, braze, weld or otherwise affix the ends of the desiredlength together (e.g. with a biocompatible cementitious organicmaterial) before cutting the braid.

Once an appropriately sized piece of the metal fabric is obtained, thefabric is deformed to generally conform to a surface of a moldingelement. Deforming the fabric will reorient the relative positions ofthe strands of the metal fabric from their initial order to a second,reoriented configuration. The shape of the molding element should beselected to deform the fabric into substantially the shape of thedesired medical device when unconstrained.

Once the molding element is assembled with the metal fabric generallyconforming to a molding surface of that element, the fabric can besubjected to a heat treatment while it remains in contact with thatmolding surface. Suitable heat treatments of Nitinol wire to set adesired shape are well known in the art. It has been found that holdinga Nitinol fabric at about 500° C. to about 550° C. for a period of about1 to about 30 minutes, depending on the softness or harness of thedevice to be made, will tend to set the fabric in its deformed state,i.e. wherein it conforms to the molding surface of the molding element.At lower temperatures the heat treatment time will tend to be greater(e.g. about one hour at about 350° C.) and at higher temperatures thetime will tend to be shorter (e.g. about 30 seconds at about 900° C.).

After the heat treatment, the fabric is removed from contact with themolding element and will substantially retain its shape in a deformedstate.

FIGS. 5A and 5B illustrate an embodiment of a medical device 10 inaccordance with the present invention. This device 10 has a generallycylindrical body portion 12 and an outwardly extending forward disk end14. The cylindrical body portion 12 is sized to be somewhat larger(about 10-30%), than the vessel to be occluded. This sizing is intendedto provide one element of anchoring the device to prevent dislodgement.The disk portion of the device 14 is intended to abut the adjacent wallsurrounding, the aperture, to prevent device movement toward thecylindrical portion direction and to assist in sealing the aperture.

The improvement over the prior art incorporates a transition diameter H,between the cylindrical portion 12, and the disk portion 14 that issmall in relationship to the cylindrical diameter B, and the diskdiameter A. This small transition diameter allows the disk portion toeasily orient itself to the vessel wall containing the aperture wherethe wall is not truly perpendicular (perpendicular +or −45 degrees).Additionally, the recessed transition diameter H within an indentation15 in the end of the cylindrical body will allow the device to conformto the anatomy in which the device is being positioned by acting like aspring member for maintaining tension between the disk and thecylindrical body. Separation between the disk and the cylindrical bodywill not impact device performance.

One application, for which this device is particularly well suited, isoccluding vessels, channels, lumens or cavities that are connected byaperture to another vessel having a wall surrounding the aperture. Onesuch condition known in the art is a patent ductus arteriosus (PDA)which is essentially a condition wherein two blood vessels, mostcommonly the aorta and pulmonary artery adjacent the heart, have a bloodflow shunt between their lumens. Blood can flow directly between thesetwo blood vessels through the passageway, compromising the normal flowof blood through the patient's vessels. Other physiologic conditions inthe body occur where it is also desirous to occlude a vessel to preventblood flow through the vessel. This device embodiment may be usedanywhere in the vasculature where the anatomical conditions areappropriate for the design.

As explained more fully below in connection with FIGS. 5A and 5B, thecylindrical shaped body 12 is adapted to be deployed within the vesselto be occluded, while the disk 14 is adapted to be positioned adjacentthe wall surrounding the aperture associated with the vessel to beoccluded. The braided metal fabric extends from the proximal disk endclamp 16, radially outward to the disk maximum diameter A and backradially inward against itself to the transitional diameter H. Thetransitional diameter extends distally a distance J whereby the fabricforms a reverse cone toward the disk with a diameter K where the fabricturns to follow parallel to the disk but spaced from the disk a distanceE, radially outward to a diameter B. The fabric continues to maintaincylindrical diameter B distally a distance D, then forming a tapersurface of angle C to a total cylindrical portion length G. The distalend clamp 18 and the proximal end clamp 16 hold the braided wire endsfrom unraveling. The proximal end clamp 16 also contains a threadedportion that reversibly connects to a delivery system (not shown) suchas a cable or shaft with mating threads at its end.

The improvement in disk flexibility and conformance to a vessel wallwhich are not perpendicular to the axis of the vessel to be occludedcomes from the disk maximum diameter A in relation to the small diameterH, or the ratio of A/H. In the prior art device of FIGS. 1A and 1B thisratio is about 1.9, but in the improved design of FIGS. 5A and 5B theratio is in the range of 3 to 30, preferably about 10 to 20-25. In theprior art design, the ratio for the cylindrical body 12 diameter B tothe disk transition diameter H is 1.0 since there is no reducedtransition diameter. In the improved design, the ratio B/H is in therange of 2-25 and preferably 10-20. This improved ratio reduces thebending force necessary to cause disk alignment to the vessel wall oralternatively, alignment of the cylindrical portion to the vessel to beoccluded. The transition diameter H has a length J which is about 2-5times the diameter H. This length J is necessary to allow a smalldimension E between the disk inner surface and the cylindrical portionproximal end wall as shown in FIG. 5A. This improves the device fit andimproves the sealing of the device. To accommodate the length J oftransition diameter H the fabric is shaped to form a conical surface atan angle L to the proximal end wall of the cylindrical portion. Thisconical surface accommodates user displacement of the cylindricalportion from adjacent the disk by cone flattening and thereby providesincreased radial expansive force for device retention on the proximalcylindrical outer diameter. Additionally, the conical surface acts as aspring to provide axial tension between the disk and cylindrical portionwhen they are displaced apart to keep the hooks 20 engaged in the wallof the vessel being occluded, thus improving device retention.

As shown in FIGS. 5A and 5B, retention hooks 20 are preferablyfabricated from Nitinol wire heat set into a hook shape at each end anda bend of about 180 degrees in the mid length segment of the wire tocreate 2 interconnected hooks. Alternatively, the hooks could be a partof the device—i.e. individual wires within the braided structure thatare isolated and formed into hooks. The ends of the hooks are orientedtoward the disk and sutured 22 or fastened by any known means to thebraided fabric on the cylindrical portion 12 of the device. The hookwires 20 are preferably about 0.007 inches in diameter and 3 mm inlength and flexible enough to be back loaded into the delivery catheteror forward loaded, if introduced in a straightened out configuration.The device may have any number of these hooks, but preferably has threepairs of hooks. The number of hooks would preferably range from 6 to 12.The hooks assist in the retention of the device by resisting motion ofthe device in the vessel in a direction that would cause the hooks toengage the tissue. The hooks 20 do not have barbs so that the engagementis reversible by movement of the device opposite to the open end of thehook. The art pertaining to vascular grafts has many examples ofalternative hooks that may be incorporated into vascular implantabledevices.

Those skilled in the art will appreciate that, in order to speed up theocclusion of the vessel device, the device may be coated with a suitablethrombogenic agent, filled with a polyester fiber or braided with anincreased number of wire strands. The prior art devices have preferablyused a polyester fiber (303 as shown in FIG. 6) within the braideddevice. This fiber easily collapses with the device for delivery througha catheter. The interwoven fiber by attachment to clot retains the clotfirmly within the device as it forms the occlusion.

The delivery device 28 shown in FIG. 6 can be used to urge the PDAocclusion device 10 through the lumen of a catheter or long introducersheath for deployment in a channel of the patient's body. When thedevice is deployed out the distal end of the catheter, the device willstill be retained by the delivery device. Once the proper position ofthe device 10 in the vessel is confirmed, the shaft of the deliverydevice 28 can be rotated about its axis to unscrew the clamp 16 from thethreaded end of delivery means. Of course the threaded connection couldbe at either end of the device depending on the anatomical situation andthe desired or available means of access to the treatment site.

The tubular braid used to fabricate occlusion devices of this inventionmay range from wire having a diameter of 0.002 to 0.005 in., preferablyin the range of 0.003 to 0.0035 in., and for a PDA device, preferably0.003 in. diameter. The number of wires in the tubular braid may varyfrom 36 to 144 but preferably is in the range of 72 to 144 and for a PDAdevice is preferably 144 wires. The pick count of the braid may varyfrom 30 to 100 and preferably from 50 to 80 and for a PDA device ispreferably 70.

The sizes of the body 12 and the disk 14 and device length can be variedas desired for differently sized vessels, channels, lumens or cavities.A table of dimensional ranges and for select devices is provided belowin mm.

TABLE I A B C D E F G H J K L Range 6 to 35 2 to 20 to 2 to 0 to 6 1 to3 3 to 1 to 8 0 to 3 to 20 to 28 70 20 25 10 20 70 PDA  8  4 45  4 1 1 6 1 2 3 20 Another 23 18 45 10 0 2 14 2 4 8 30

By keeping the PDA device 10 attached to the delivery means, theoperator may still retract the device back into a delivery sheath forrepositioning if it is determined that the device is not properlypositioned in the first attempt. This threaded attachment will alsoallow the operator to control the manner in which the device 10 isdeployed out of the distal end of the delivery catheter. As explainedbelow, when the device exits the delivery catheter it will tend toresiliently return to a preferred expanded shape which was set when thefabric was heat treated. When the device springs back into this shape,it may tend to act against the distal end of the catheter, effectivelyurging itself forward beyond the end of the catheter. This spring actioncould conceivably result in improper positioning of the device. Sincethe threaded clamp 16 can enable the operator to maintain a hold on thedevice during deployment, the spring action of the device can becontrolled and the operator can control the deployment to ensure properpositioning.

Optionally, but not considered a requirement, the device as shown inFIG. 6, could be configured with a hollow inner clamp member 23 at bothwire ends and a outer clamp proximal member 21 and a distal outer clampmember 26. The wire ends 24 are crimped between the inner and outerclamp members 21, 26 by swaging or alternatively may be bonded or weldedbetween the clamp members. The inner clamp member is tubular and issized with an inside diameter to freely pass a push wire 27. The distalouter clamp member 26 is sized with an inside diameter sufficient toaccommodate the braid wire ends 24 surrounding the inner clamp memberprior to swaging. The distal end on the distal outer clamp member 26 issolid (closed end) to accept the push force from the push wire 27 placedthrough both inner clamp members against this solid end. The proximalouter clamp member 21 is shown with external threads to reversiblyconnect to the delivery system 28, which is preferably a nylon blockco-polymer such as Pebax with a 0.001 in. braided wire over the Pebaxinner tube extrusion, followed by another outer layer of Pebax to coverthe braid. The delivery catheter/sheath 29 may be similarly constructedexcept larger in diameter to accommodate the passage of the device 10and delivery system 28. Such construction is typical in intravascularcatheters where a flexibility and torque transmission are needed.

Optionally, the delivery catheter sheath 29 may have a 0.001 in. thicklayer of PTFE to lower friction for ease of device passage therethrough.The hollow delivery system sized to allow a push wire 27, made ofstainless steel 0.008-0.014 in. to pass through the delivery system andthe proximal clamp and to engage the distal clamp to push the distalclamp away from the proximal clamp to elongate the device, facilitaterelease of the hooks and facilitate recapture of the device into thedelivery sheath 29. The distal end of the push wire 27 and the distalinner clamp 23 may be designed to attach by a threaded connection orother reversible means to ensure the wire does not inadvertently getpositioned proximal to the distal inner clamp 23. It is also anticipatedthat a spring positioned between the delivery system 28 and the pushwire 27 could maintain the push wire against the distal outer clamp 26.By means of the delivery system 28 maintaining control of the proximalend of the device 10 and the push wire 27 being able to exert a pushforce on the distal end of the device, the device may be elongated orallowed to self expand and contract in length as desired. This aids inrepositioning with the hooks being easily released by pushing on thepush wire to force the device in the distal direction. This also aids inwithdrawing the device back into the sheath 29 should the need occur,such as in incorrect device sizing to the anatomy.

FIGS. 7A-C schematically illustrates how a medical device 10, generallyas outlined above, can be used to occlude a vessel having a wallsurrounding an aperture to a vessel, channel, lumen, or cavity which isto be occluded. The device 10, in its collapsed for deliveryconfiguration and attached to the delivery system 28, can be passedthrough a delivery catheter 29 such that the distal end of the deliverycatheter is adjacent the aperture 30 in the vessel wall 31 as shown inFIG. 7A. The delivery system 28 is advanced distally while holding backthe delivery catheter 29 to urge the distal end of the device 10 outfrom the catheter 29 to elastically self expand substantially to itspredetermined heat set molded state, where by it contacts the vesselwall. At this point the distal end of catheter 29 may react to theexpansion force and move proximally a small amount as shown in FIG. 7B.The hooks 20 begin to make contact with the vessel wall to hold thedevice in place. If needed to be positioned distally this can be donebecause the hooks will release in that direction. In FIG. 7C the deviceis full exited from the catheter 29 but still attached to the deliverysystem 28. As shown in this figure the disk 14 self aligns with the wall31 by pivoting about the small diameter H. After the device ispositioned as desired, the delivery system is disconnected by turningthe delivery system 28 in a direction to release the threaded connectionat the proximal end clamp 16.

The body portion 12 should be sized so that it will frictionally engagethe lumen of the vessel to be occluded. The device 10 will then be heldin place by the combination of the friction between the body portion andthe lumen of the vessel and the hooks 20 which engage the wall. Over arelatively short period of time, thrombi will form in and on the device10 and the thrombi will occlude the vessel. Those skilled in the artwill appreciate that in order to speed up the occlusion of the vesseldevice, the device may be coated with a suitable thrombogenic agent,filled with a polyester fiber or braided with an increased number ofwire strands.

Pulmonary vascular occlusive disease and pulmonary atrial hypertensiondevelops in adulthood. Patients with secundum atrial septal defect (ASD)with a significant shunt are operated upon ideally at five years of ageor whenever a diagnosis is made in later years. With the advent of twodimensional echocardiography and Doppler color flow mapping, the exactanatomy of the defect can be visualized. The size of the defect willcorrespond to the selected size of the ASD occlusive device to be used.

FIGS. 2 through 4 illustrate an alternate preferred embodiment of amedical occlusive device in accordance with the present invention forcorrecting an ASD. It is proposed that this device 300 may also be wellsuited in occluding defects known in the art as patent foraman ovale(hereinafter PFO) or for ventricular septal defects (VSD). Withreference to FIGS. 2-4, the device 300 in its relaxed, unstretched statehas two disks 302 and 304 aligned in spaced relation, linked together bya short cylinder 306. The length of the cylindrical segment 306preferably approximates the thickness of the atrial septum, and rangesbetween 2 to 20 mm. The proximal 302 and distal 304 disks preferablyhave an outer diameter sufficiently larger than the shunt to preventdislodging of the device. The proximal disk 302 has a relatively flatconfiguration, whereas the distal disk 304 is cupped towards theproximal end slightly overlapping the proximal disk 302. The improvementin the device design over the prior art is shown in FIG. 3 which is across-sectional view of the device of FIG. 2. In the prior art design,the fabric of the short cylinder 306 connected with the inside wallfabric of each disk at the diameter of the short cylinder. In theimproved device design of the present invention, the short cylinderconnects with the disk walls at a small diameter 309 which is muchsmaller than the diameter of the short cylinder which is much smallerthan the diameter of the disk. This allows the disk to easily pivotabout diameter 309 to allow the disks to align themselves withanatomical vessel walls that are not perpendicular (at an angle) to theaperture there between.

The ends of this braided metal fabric device 300 are welded or clampedtogether with clamps 308 and 310, as described above, to avoid fraying.Of course the ends may alternately be held together by other meansreadily known to those skilled in the art. The clamp 310 tying togetherthe wire strands at the proximal end also serves to connect the deviceto a delivery system. In the embodiment shown, the clamp 310 isgenerally cylindrical in shape and has a recess for receiving the endsof the metal fabric to substantially prevent the wires comprising thewoven fabric from moving relative to one another. The clamp 310 also hasa threaded surface within the recess. The threaded recess is adapted toreceive and engage the threaded distal end of a delivery device 28 (FIG.6).

The ASD occlusion device 300 of this embodiment of the invention canadvantageously be made in accordance with the method outlined above. Thedevice 300 is preferably made from a 0.005 inch Nitinol wire mesh. Thebraiding of the wire mesh may be carried out with 28 picks per inch at ashield angle of about 64 degrees using a Maypole braider with 72 wirecarriers. The stiffness of the ASD device 300 may be increased ordecreased by altering the wire size, the shield angle, the pick size,the number of wire carriers or the heat treatment process.

Those skilled in the art will recognize from the preceding discussionthat the cavities of the mold must be shaped consistent with the desiredshape of the ASD device. In the case of the improvement the mold must beshaped to provide for forming the small pivot diameter 309.

FIGS. 8A through 8C illustrate an ASD device having a modifiedconfiguration. The proximal disk 302 is a mirror image of distal disk304′. The distance separating the proximal and distal disks 302′ and304′ is less than the length of the cylindrical segment 306. The cupshape of the disk, as illustrated in FIG. 8B, ensures complete contactbetween the occlusion device 300′ and the atrial septum. As such, a neoendocardium layer of endothelial tissue forms over the occlusion device300, thereby reducing the chance of bacterial endocarditis.

In order to speed up the occlusion of the vessel device, the device maybe coated with a suitable thrombogenic agent, filled with a polyesterfiber or braided with an increased number of wire strands. A polyesterfiber 303 (as shown in FIGS. 4 and 8 c) is optionally placed within thebraided device to speed the clotting process. This fiber easilycollapses with the device for delivery through a catheter and can beplaced in the disks, or middle portions or a combination of portions.The interwoven fiber by attachment to clot retains the clot firmlywithin the device as it forms the occlusion.

The use of the device will now be discussed in greater detail withreference to FIGS. 9, 10 and the delivery device of FIG. 7C. The devicemay be delivered and properly placed using two dimensionalechocardiography and Doppler color flow mapping. The delivery device 28of FIG. 7C can take any suitable shape, preferably comprising anelongated flexible metal shaft similar to a conventional guidewire ormay be a hollow shaft similar 27 as described for FIG. 6 above. Thedelivery device 28 is used to advance the ASD occlusion device 300through the lumen 25 of a small diameter cylindrical tube, such as adelivery catheter 29 for deployment. The ASD device 300′ is loaded intothe lumen 25 by stretching the same to put it in an elongated condition.The device may be inserted into the lumen 25 during the procedure orpreassembled at a manufacturing facility, in that the devices of thepresent invention do not take on a permanent set when maintained in acompressed state.

FIG. 10 illustrates how the disks 302′ and 304′ can assume anon-parallel relationship to intimately engage opposed walls of a septum318 of non-uniform thickness and with the central cylindrical portion306′ expanded against the walls defining the ASD. FIG. 10 depicts theinventive device 300′ occluding an ASK in the heart.

From a femoral vein approach, the delivery catheter 29 is passed acrossthe ASD. The device 300′ is advanced through the delivery catheter untilthe distal end 304′ becomes unconstrained on exiting the end of thecatheter, whereupon it assumes its disk-like shape in the left atrium.The delivery catheter 29 is then pulled back in the proximal directionacross the ASD and the delivery device 28 is held stationary, urging thedistal disk 304′ against the septum 318.

The delivery catheter 29 is then further pulled away from the septum318, allowing the proximal disk 302′ to extend out of the deliverycatheter 29, where it resiliently returns to its predefined expandeddisk-like shape. In this manner, the ASD device 300′ is positioned suchthat the distal disk 304′ presses against one side of the septum 318while the proximal disk 302′ presses against the other side of theseptum 318.

In order to increase its occluding ability, the device can containpolyester fibers 303′. (See FIG. 8C). In instances where the device isimproperly deployed on a first try, the device 300′ may be recovered bypulling the delivery device 28 proximally, thereby retracting the device300′ back into the delivery catheter 29 prior to a second attempt atpositioning the device 300′ relative to the defect.

When the ASD occluding device 300′ is properly placed, the physicianrotates the delivery device 28, unscrewing the delivery device 28 fromthe clamp 310′ of the occluding device 300′. The threads on the clamp310′ are such that the rotation of the delivery device 28 unscrews thedelivery device from the clamp 310′ of the occluding device 300′, ratherthan merely rotating the occluding device 300′. As noted above, inalternate embodiments, the threaded clamp can enable the operator tomaintain a hold on the device during deployment, or enables the operatorto control the spring action during deployment of the device to ensureproper positioning.

Generally, the method in accordance with the present invention furtherincludes a method of treating a physiological condition of a patient. Inaccordance with this method, a medical device suitable for treating thecondition, which may be substantially in accordance with one of theembodiments described in detail above, is selected. For example, if apatent ductus arteriosus is to be treated, the PDA occlusion device 10of FIGS. 5A, 5B and 6 can be selected. Once the appropriate medicaldevice is selected, a catheter may be positioned within a channel inpatient's body to place the distal end of the catheter adjacent thedesired treatment site, such as immediately adjacent (or even within)the passageway or channel of the PDA.

The medical device can be collapsed into its collapsed configuration andinserted into the lumen of the catheter. The collapsed configuration ofthe device may be of any shape suitable for easy passage through thelumen of a catheter and proper deployment out the distal end of thecatheter. For example, the devices shown in FIGS. 2, 3, 4, 5A, 5B, 6 and8A-8C have a relatively elongated collapsed configuration wherein thedevices are stretched along their axes as shown in FIGS. 4 and 8C. Thiscollapsed configuration can be achieved simply by stretching the devicegenerally along its axis, e.g. by manually grasping the clamps 308 and310 and pulling them apart, which will tend to collapse the expandeddiameter portions 302 and 304 of the device inwardly toward the device'saxis. The PDA occlusion device 10 of FIGS. 2 and 3 also operates in muchthe same fashion and can be collapsed into its collapsed configurationfor insertion into the catheter by applying tension generally along theaxis of the device. In this regard, these devices 10 and 300 are notunlike “Chinese handcuffs”, which tend to constrict in diameter underaxial tension.

Once the medical device is collapsed and inserted into the catheter, itmay be urged along the lumen of the catheter toward the distal end ofthe catheter. This may be accomplished by using a delivery system or thelike removably connected to the device to urge it along the catheter.When the device begins to exit the distal end of the catheter, which ispositioned adjacent the desired treatment site, it will tend toresiliently return substantially entirely to its preset expandedconfiguration. Superelastic alloys, such as Nitinol, are particularlyuseful in this application because of their ability to readily return toa particular configuration after being elastically deformed to a greatextent. Hence, simply urging the medical device out of the distal end ofthe catheter tends to properly deploy the device at the treatment site.

Although the device will tend to resiliently return to its initialexpanded configuration (i.e. its shape prior to being collapsed forpassage through the catheter), it should be understood that it may notalways return entirely to that shape. For example, the member 12 of FIG.5A is intended to have a maximum outer diameter in its expandedconfiguration at least as large as and preferably larger than, the innerdiameter of the lumen in which it is to be deployed. If such a device isdeployed in a vessel having a small lumen, the lumen will prevent thedevice from completely returning to its expanded configuration.Nonetheless, the device would be properly deployed because it wouldengage the inner wall of the lumen to seat the device therein, asdetailed above.

If the device is to be used to permanently occlude a channel in thepatient's body, such as the devices 10 and 300 described above may be,one can simply disconnect the delivery system (example shown FIG. 6) byreversing the reversible connection to the device and retract thecatheter and delivery system from the patient's body. This will leavethe medical device deployed in the patient's vascular system so that itmay occlude the blood vessel or other channel in the patient's body.

While a preferred embodiment of the present invention has beendescribed, it should be understood that various changes, adaptations andmodifications may be made therein without departing from the spirit ofthe invention and the scope of the appended claims.

For example, it is anticipated that in a double disk design that it maybe desirable that only one end of the device have a small transitiondiameter between the disk and the adjacent middle cylindrical portion.It is also anticipated that the cylindrical middle or body portion maybe non-concentric to one or both disks. It is further anticipated thatthe cylindrical portion could be barrel shaped, concave, convex, taperedor a combination of shapes without departing from the invention herein.Likewise the cylindrical portion distal and proximal ends could havediffering shapes than the recessed conical shape described while stillretaining the benefits described.

That which is claimed:
 1. A collapsible medical device comprising: atubular metal fabric including a plurality of braided metal strands anddefining a proximal end and a distal end, the tubular metal fabrichaving a collapsed configuration for delivery through a channel in apatient's body and an expanded configuration for substantially creatingan occlusion of an opening in the patient's body, wherein, in theexpanded configuration, the tubular metal fabric defines a first portionhaving a first diameter proximate the proximal end, a second portionhaving a second diameter proximate the distal end, and a third portionhaving a third diameter extending between the first portion and thesecond portion, wherein the third diameter is less than the seconddiameter and the second diameter is less than the first diameter,wherein the second portion has a preset shape that is configured tomaintain a tension between the first portion and the second portion whenthe medical device is positioned within the opening in the patient'sbody.
 2. The collapsible medical device of claim 1, wherein a distalside of the second portion comprises a concave tapered surface.
 3. Thecollapsible medical device of claim 1, wherein the third portion is atleast partially recessed within the second portion.
 4. The collapsiblemedical device of claim 1, wherein the second portion comprises at leastone hook configured to engage tissue proximate the opening in thepatient's body when the medical device is in place.
 5. The collapsiblemedical device of claim 1, wherein the second portion comprises aconical surface extending in a proximal direction from a center of thetubular metal fabric.
 6. The collapsible medical device of claim 1,wherein a ratio of the first diameter to the third diameter isapproximately 3 to
 30. 7. The collapsible medical device of claim 6,wherein the ratio of the first diameter to the third diameter isapproximately 20 to
 25. 8. The collapsible medical device of claim 1,wherein a ratio of the second diameter to the third diameter isapproximately 2 to
 25. 9. The collapsible medical device of claim 8,wherein the ratio of the second diameter to the third diameter isapproximately 10 to
 20. 10. The collapsible medical device of claim 1,further comprising an occluding fiber retained within at least one ofthe first portion or the second portion.
 11. A collapsible medicaldevice comprising: a first portion proximate one of a proximal end or adistal end of the medical device; a second portion located opposite ofthe first portion proximate one of the proximal end or the distal end,the second portion including a conical surface; a third portionextending between the first portion and the second portion, the thirdportion having a diameter less than a diameter of the first portion andless than a diameter of the second portion, wherein the first portion,the second portion, and the third portion are formed from a tubularmetal fabric including plurality of braided metal strands, the tubularmetal fabric having a collapsed configuration for delivery through achannel in a patient's body and an expanded configuration forsubstantially creating an occlusion of an opening in the patient's body.12. The collapsible medical device of claim 11, wherein the firstportion is disk shaped.
 13. The collapsible medical device of claim 11,wherein the second portion is cylindrically shaped.
 14. The collapsiblemedical device of claim 11, wherein the conical surface extends out froma center of the tubular fabric and towards the first portion.
 15. Thecollapsible medical device of claim 11, wherein an angle of the conicalsurface with respect to a plane perpendicular to a longitudinal axis ofthe medical device is approximately 20° to 70°.
 16. The collapsiblemedical device of claim 11, wherein the second portion comprises aconcave tapered surface.
 17. The collapsible medical device of claim 16,wherein an angle of the concave tapered surface with respect to a planeperpendicular to a longitudinal axis of the medical device isapproximately 20° to 70°.
 18. The collapsible medical device of claim16, wherein an angle of the concave tapered surface with respect to aplane perpendicular to a longitudinal axis of the medical device isgreater than an angle of the conical surface with respect to the plane.19. The collapsible medical device of claim 11, wherein the secondportion comprises at least one hook configured to engage tissueproximate the opening in the patient's body when the medical device isin place.
 20. The collapsible medical device of claim 19, wherein the atleast one hook comprises an individual strand of the braided metalstrands that is isolated and formed into the at least one hook.